While CATaLOG allows me to see when my cats go in and out of the house and what their favourite time and day is, it doesn't actually let me see where they go. To remedy this, I bought an i-gotU GPS tracker. While the GT-100 (version 1) of this product got pretty negative reviews, the GT-120 version (version 2) seems to get better ones, and this is the one Maplin stocked for £40. Here it is:

I'm glad I've been alive long enough to remember times before GPS and mobile phones and still don't take them for granted. The whole package is smaller than a matchbox and contains a GPS patch antenna, a GPS receiver, a microcontroller, storage for up to 64,000 waypoints, firmware which not only controls the device but also stores config values and allows data to be pulled off the device, a USB interface and a lithium ion battery plus charging circuitry. Not to mention this tiny thing is computing where it is from signals sent from satellites 12,552 miles above it. Incredible.

The box / website states Windows support only, but happily there is a fairly new, actively maintained project called igotu2gpx which gives command line tools for Linux / MacOS X to pull the data off the device and translate it into a standard GPX format usable by sites like the excellent http://www.gpsvisualizer.com.

I've done a couple of test routes and it seems to be pretty accurate to within 5 metres or so. It's logging the data every 6 seconds at the moment (which gives around 8 hours battery life) but this can be increased or decreased depending on the application.

Once I've got a harness for the cats I'll be attaching it to them, probably overnight, to see what they get up to. :)